Dual Nature Of Radiation And Matter Ques 29
29. Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be $3.57 $ $V$. The threshold frequency of the materials is :
[2012]
(a) $4 \times 10^{15} $ $Hz$
(b) $5 \times 10^{15} $ $Hz$
(c) $1.6 \times 10^{15} $ $Hz$
(d) $2.5 \times 10^{15} $ $Hz$
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Answer:
Correct Answer: 29.(c)
Solution:
- (c) $n \to 2-1$
$E=10.2 $ $ eV$
$k E=E-\phi$
$Q=10.20-3.57$
$h v_0=6.63 $ $eV$
$v_0=\frac{6.63 \times 1.6 \times 10^{-19}}{6.67 \times 10^{-34}}=1.6 \times 10^{15}$ $ Hz$
BETA
